Method for making heater

ABSTRACT

A method for making a heater is provided. A support and a flexible substrate are provided. The flexible substrate is fixed on a surface of the support. A carbon nanotube film is drawn from a carbon nanotube array. One end of the carbon nanotube film is attached on the flexible substrate. The carbon nanotube film is wrapped around the support by whirling the support to form a carbon nanotube layer. The carbon nanotube layer includes a plurality of carbon nanotubes aligned in a first direction. The flexible substrate is heated to a temperature of about 80° C. to about 120° C. The flexible substrate is then shrunk along the first direction. A plurality of electrodes are electrically connected with the carbon nanotube layer.

RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. §119 fromChina Patent Application No. 201210130016.5, filed on Apr. 28, 2012, inthe China Intellectual Property Office, the disclosure of which isincorporated herein by reference. The application is also related tocopending applications entitled, “HEATER,” filed on Feb. 28, 2013, withapplication Ser. No. 13/779,752 and “METHOD FOR MAKING HEATER,” filed onApr. 19, 2013, with application Ser. No. 13/866,232.

BACKGROUND

1. Technical Field

The present disclosure relates to a method for making a heater.

2. Description of Related Art

A typical heater includes a heating element and at least two electrodes.The heating element is electrically connected with the two electrodes.The heating element generates heat when a voltage is applied to it. Theheating element is often made of a metal such as tungsten. Metals, whichhave good conductivity, and can generate a lot of heat even when a lowvoltage is applied. However, metals can easily oxidize, thus the heaterelement has a short life. Furthermore, because metals have a relativehigh density, the heating element made of metals are heavy, which limitsapplications of such heater.

Therefore there is room for improvement in the art.

BRIEF DESCRIPTION OF THE DRAWING

Many aspects of the present disclosure can be better understood withreference to the following drawings. The components in the drawings arenot necessarily to scale, the emphasis instead being placed upon clearlyillustrating the principles of the present embodiments.

FIG. 1 is a schematic view showing one embodiment of a process of makinga heater.

FIG. 2 is a scanning electron microscope (SEM) photo of a carbonnanotube film.

FIG. 3 is a schematic view of one embodiment of the heater.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “another,” “an,” or “one” embodiment in this disclosure are notnecessarily to the same embodiment, and such references mean at leastone.

Referring to FIGS. 1 and 2, an embodiment of a method for making aheater 10 is provided. The method includes the steps of:

S1: providing a support 20 and a flexible substrate 11, and wrapping theflexible substrate 11 on a surface of the support 20;

S2: drawing a carbon nanotube film 14 from a carbon nanotube array 12,and attaching one end of the carbon nanotube film 14 on the flexiblesubstrate 11;

S3: wrapping the carbon nanotube film 14 around the support 20 byrotating the support 20 to form a carbon nanotube layer 15 around theflexible substrate 11;

S4: separating the flexible substrate 11 from the support 20 and thecarbon nanotube layer 15, the carbon nanotube layer 15 includes aplurality of carbon nanotubes aligned in a first direction;

S5: shrinking the flexible substrate 11 along the first direction byheating the flexible substrate 11 to a temperature ranging from about80° C. to about 120° C., and

S6: electrically connecting a plurality of electrodes 16 with the carbonnanotube layer 15.

In step S1, the support 20 can have a column structure, a triangularprism structure, or a cuboid structure. In one embodiment according toFIG. 2, the support 20 has a column structure. The support 20 can rotatearound its axis, driven by an electric motor. In the embodimentaccording to FIG. 1, the flexible substrate 11 wraps on a surface of thesupport 20 to form a cylinder structure. The flexible substrate 11 is aheat-shrinkable material. That is, a size of the heat-shrinkablematerial can shrink when the heat-shrinkable material is heated to atemperature. The material of the flexible substrate 11 can beacrylonitrile-butadiene-styrene (ABS), ethylene-vinyl acetate copo(EVA), polyethylene terephthalate (PET) or polyolefin. In oneembodiment, the material of the flexible substrate 11 is polyolefin. Alength of the flexible substrate 11 is about 40 centimeters, and a widthof the flexible substrate 11 is about 30 centimeters.

In one embodiment, the step S1 includes sub-steps of:

S11: fixing one end of the flexible substrate 11 on the surface of thesupport 20; and

S12: rotating the support 20 to wrap the flexible substrate 11 aroundthe circumferential surface of the support 20.

After the flexible substrate 11 is wrapped on the support 20, anadhesive layer 17 can be formed on the circumferential surface of theflexible substrate 11. A material of the adhesive layer 17 can be silicagel.

In step S2, the step includes sub-steps of:

S21: providing a carbon nanotube array 12 formed on a separate substrate13;

S22: pulling out a carbon nanotube film 14 from the carbon nanotubearray 12; and

S23: attaching one end of the carbon nanotube film 14 on the flexiblesubstrate 11, and the carbon nanotube film 14 is kept stretched betweenthe carbon nanotube array 12 and the flexible substrate 11.

In step S21, the carbon nanotube array 12 includes carbon nanotubesaligned in a same direction. The aligned direction of the carbonnanotubes in the carbon nanotube array is substantially perpendicular tothe top surface of the substrate 13.

In step S22, the carbon nanotube film 14 can be pulled out by the stepsof:

S221: selecting some carbon nanotubes having a predetermined width fromthe array of carbon nanotubes; and

S222: pulling the carbon nanotubes to obtain nanotube segments atuniform speed to achieve the carbon nanotube film 14.

In step S221, the carbon nanotubes are substantially parallel to eachother. The carbon nanotubes can be selected by using an adhesive tape asthe tool to contact the carbon nanotubes. In step S222, the pullingdirection is substantially perpendicular to the growing direction of thesuper-aligned array of carbon nanotubes. The carbon nanotube film 14 canbe pulled out continuously from the carbon nanotube array 12. The carbonnanotube film includes a plurality of carbon nanotubes joined end toend. The plurality of carbon nanotubes joined end to end means thatopposite ends of a carbon nanotube are continuously connected with theends of two other carbon nanotubes. The plurality of carbon nanotubesare substantially parallel with each other. The plurality of carbonnanotubes in the carbon nanotube film 14 are substantially parallel witha surface of the carbon nanotube film 14. The plurality of carbonnanotubes in the carbon nanotube film 14 are joined with each other byvan der Waals attractive force. The plurality of carbon nanotubes in thecarbon nanotube 14 can be pure, meaning there is no impurity attached oneach carbon nanotube. The carbon nanotube film can consist of theplurality of carbon nanotubes. The carbon nanotube film is afree-standing structure, that is, the carbon nanotube film can besuspended in the air with two ends of the carbon nanotube film 14 fixedwithout any support between and still maintain its structural integrity.

In step S222, during the pulling process, as the initial carbonnanotubes are drawn out, other carbon nanotubes are also drawn out endto end due to van der Waals attractive force between ends of adjacentsegments. This process of pulling produces a substantially continuousand uniform carbon nanotube film having a predetermined width. The widthof the carbon nanotube film depends on a size of the carbon nanotubearray. The length of the carbon nanotube film can be set as desired. Inone embodiment, when the substrate is a 4 inch type wafer, a width ofthe carbon nanotube film can be in a range from about 1 centimeter (cm)to about 10 cm, the length of the carbon nanotube film can reach about120 m, and the thickness of the carbon nanotube film can be in an rangefrom about 0.5 nm to about 100 microns.

In step S23, the carbon nanotube film 14 is suspended between the carbonnanotube array 12 and the flexible substrate 11. In one embodiment, thecarbon nanotubes in the carbon nanotube film 14 are pure and adhesive,and the carbon nanotube film 14 can be directly attached on the surfaceof the flexible substrate 11. In another embodiment, the carbon nanotubefilm 14 is attached on the flexible substrate 11 via the adhesive layer17. One part of the carbon nanotube film 14 is suspended between thecarbon nanotube array 12 and the support 20. The carbon nanotubes in theone part of the carbon nanotube film 14 suspended between the carbonnanotube array and the support 20 are oriented in substantially the samedirection substantially perpendicular to an axis of the support 20.

In step S2, after the end of carbon nanotube film 14 is attached on theflexible substrate 11, an angle can be defined between the surface ofthe carbon nanotube film 14 and the aligned direction of the carbonnanotubes in the carbon nanotube array 12. The carbon nanotubes in thecarbon nanotube film 14 are substantially parallel with the surface ofthe carbon nanotube film 14. The angle can be in a range from about 60degrees to about 90 degrees. In one embodiment, the angle is about 97degrees.

In step S3, the support 20 rotates around its axis, and the carbonnanotube film 14 is pulled out continuously from the carbon nanotubearray 12 and wraps around the support 20 and a surface of the flexiblesubstrate 11. A rotating speed of the support 20 is less than 15 m/s. Inone embodiment, the rotating speed is about 0.5 m/s. The carbon nanotubelayer 15 can be formed by winding the carbon nanotube film 14continuously around the flexible substrate 11. Thus, a plurality oflayers of carbon nanotube film 14 can be formed. The carbon nanotubelayer 15 includes the plurality of layers of carbon nanotube films 14joined with each other by van der Waals attractive force. The layers ofthe carbon nanotube films 14 can be adjusted by changing the rotatingrounds of the support 20. In one embodiment, the carbon nanotube layer15 includes 200 layers of carbon nanotube films 14. The carbon nanotubelayer 15 is fixed on the flexible substrate 11 via the adhesive layer17. A pressing force can be applied on the carbon nanotube layer 15 tofill the adhesive layer 17 into the carbon nanotube layer 15, and thecarbon nanotube layer 15 can combine tightly with the flexible substrate11. In one embodiment, the pressing force is applied by a soft brush(not shown). The soft brush can brush the carbon nanotube layer 15 asthe support 20 rotates.

In step S4, the flexible substrate 11 with the carbon nanotube layer 15is separated from the support 20. The carbon nanotube layer 15 isattached on the surface of the flexible substrate 11. The surface can bea circumferential surface. The carbon nanotube layer 15 is attached onthe circumferential surface of the flexible substrate 11. The flexiblesubstrate 11 and the carbon nanotube layer 15 are both wrapped aroundthe support 20 before they are separated from the support 20. Theflexible substrate 11 and the carbon nanotube layer 15 are cut along aline which is substantially parallel with the axis of the support 20.Thus, the flexible substrate 11 unfolds to have a planar structure. Thecarbon nanotube layer 15 is attached on the circumferential surface ofthe substrate 11. The flexible substrate 11 and the carbon nanotubelayer 15 can be cut by a mechanical method or by an etching method. Inone embodiment, the flexible substrate 11 and the carbon nanotube layer15 are cut by a laser.

In step S5, the carbon nanotube layer 15 and the flexible substrate 11can be heated in a furnace to shrink the flexible substrate 11 along thefirst direction. After the flexible substrate 11 shrinks along the firstdirection, the carbon nanotube layer 15 also shrinks along the firstdirection. Thus, a plurality of wrinkles are formed in the carbonnanotube layer 15. Each of the plurality of wrinkles has a linearstructure, and is oriented along a second direction. The seconddirection is substantially perpendicular with the first direction. Thecarbon nanotubes in the carbon nanotube layer 15 are oriented along thefirst direction. In the embodiment disclosed above, the material offlexible substrate 11 is polyolefin. The flexible substrate 11 is heatedto about 100° C. The length of the flexible substrate 11 shrinks to 50%of its original length.

In one embodiment, an adhesive layer 17 is applied between the flexiblesubstrate 11 and the carbon nanotube layer 15. After the flexiblesubstrate 11 is separated from the support 20, the flexible substrate 11with the adhesive lay 17 and the carbon nanotube layer 15 thereon can beput into a solidifying apparatus for about 10 minutes to about 20minutes.

In step S6, the plurality of electrodes 16 are located on two oppositeends of the flexible substrate 11. The carbon nanotube layer 15 includesa first end and a second end opposite to the first end. The carbonnanotubes in the carbon nanotube layer 15 are substantially orientedfrom the first end to the second end. The plurality of electrodes 16 areelectrically connected with the first end and the second end. The carbonnanotubes in the carbon nanotube layer 15 are substantially orientedfrom the electrodes 16 electrically connected with the first end to theelectrodes 16 electrically connected with the second end. A shape of theelectrodes 16 can be a square, a rectangle, linear, or round. Theplurality of electrodes 16 are located apart from each other. Theplurality of electrodes 16 can be formed by a spraying method, electricplating method, or chemical plating method.

In another embodiment, an organic solvent can be applied on the carbonnanotube layer 15 to soak the carbon nanotube layer 15, after step S6 orbefore step S6. The organic solvent can be dropped onto the carbonnanotube layer 15. After being soaked by the organic solvent, theadjacent paralleled carbon nanotubes in the carbon nanotube layer 15will bundle together, due to the surface tension of the organic solventas the organic solvent volatilizes. The carbon nanotubes in the carbonnanotube layer 15 can combine tightly via van der Waals attractiveforce. The carbon nanotube layer 15 can also combine with the flexiblesubstrate 11 tightly after being soaked by the organic solvent. Theorganic solvent can be volatile, such as ethanol, methanol, acetone,dichloromethane, chloroform, or any appropriate mixture thereof.

In another embodiment, step S6 includes sub-steps of:

S61: cutting the first end and the second end of the carbon nanotubelayer 15 and the flexible substrate 11 connected with the first end andthe second end to form a plurality of linear structures;

S62: providing a plurality of electrodes 22, and each of the pluralityof electrodes 22 clips one linear structure and is used as an electrode.

In step S61, each of the linear structure has a width of about 7millimeters, and a length of about 10 millimeters.

In step S62, in one embodiment, the electrodes 22 have a clampingstructure. One linear structure is inserted into the electrode 22 andclamped by the electrode 22. Each of the electrodes 22 adjacent to thefirst end is electrically connected with a lead 21. A material of theplurality of electrode 22 is conductive. In one embodiment, a resistancebetween one electrode 22 and the linear structure is about 0.1 Ω.

Finally, it is to be understood that the above-described embodiments areintended to illustrate rather than limit the present disclosure.Variations may be made to the embodiments without departing from thespirit of the present disclosure as claimed. Elements associated withany of the above embodiments are envisioned to be associated with anyother embodiments. The above-described embodiments illustrate the scopeof the present disclosure but do not restrict the scope of the presentdisclosure.

Depending on the embodiment, certain of the steps of methods describedmay be removed, others may be added, and the sequence of steps may bealtered. The description and the claims drawn to a method may includesome indication in reference to certain steps. However, the indicationused is only to be viewed for identification purposes and not as asuggestion as to an order for the steps.

What is claimed is:
 1. A method for making a heater, the methodcomprising: S1: providing a support and a flexible substrate, wrappingthe flexible substrate on a surface of the support; S2: drawing a carbonnanotube film from a carbon nanotube array, and attaching one end of thecarbon nanotube film on the flexible substrate; S3: wrapping the carbonnanotube film around the support by rotating the support to form acarbon nanotube layer around the flexible substrate; S4: separating theflexible substrate from the support and the carbon nanotube layer, thecarbon nanotube layer includes a plurality of carbon nanotubes alignedin a first direction; S5: shrinking the flexible substrate along thefirst direction by heating the flexible substrate to a temperatureranging from about 80° C. to about 120° C., and S6: electricallyconnecting a plurality of electrodes with the carbon nanotube layer. 2.The method of claim 1, wherein in the step S1, the flexible substratewraps around the surface of the support.
 3. The method of claim 2,wherein the step S1 comprises sub-steps of: fixing one end of theflexible substrate on the surface of the support; and rotating thesupport to wrap the flexible substrate on the support.
 4. The method ofclaim 3, wherein the flexible substrate comprises a first side and asecond side, the first side of the flexible substrate is stretched andthe second side is attached on the surface of the support, and theflexible substrate is wrapped around the support.
 5. The method of claim2, wherein an adhesive layer is formed on an exposed surface of theflexible substrate.
 6. The method of claim 1, wherein the step S2comprises sub-steps of: providing a carbon nanotube array formed on asubstrate; pulling out a carbon nanotube film from the carbon nanotubearray; and attaching one end of the carbon nanotube film on the flexiblesubstrate, wherein the carbon nanotube film is kept stretched betweenthe carbon nanotube array and the flexible substrate.
 7. The method ofclaim 6, wherein the carbon nanotube array comprises a plurality ofcarbon nanotubes aligned in a same direction, and the aligned directionof the carbon nanotubes in the carbon nanotube array is substantiallyperpendicular with the substrate.
 8. The method of claim 6, wherein thecarbon nanotube film is pulled out by the steps of: selecting some ofthe carbon nanotubes having a predetermined width from the carbonnanotube array; and pulling the carbon nanotubes to obtain nanotubesegments at uniform speed to achieve the carbon nanotube film.
 9. Themethod of claim 6, wherein when attaching one end of the carbon nanotubefilm on the flexible substrate, the carbon nanotube film is suspendedbetween the carbon nanotube array and the flexible substrate.
 10. Themethod of claim 6, wherein after the one end of carbon nanotube film isattached on the flexible substrate, an angle defined by a surface of thecarbon nanotube film and the aligned direction of the carbon nanotubesin the carbon nanotube array is in a range from about 60 degrees toabout 90 degrees.
 11. The method of claim 1, wherein in the step S3, thesupport rotates around its axis, and the carbon nanotube film is pulledout continuously from the carbon nanotube array and wraps around thesupport continuously.
 12. The method of claim 11, wherein a rotatingspeed of the support is less than 15 m/s.
 13. The method of claim 1,wherein an adhesive layer is formed on an exposed surface of theflexible substrate before the end of the carbon nanotube film isattached on the flexible substrate.
 14. The method of claim 13, whereina pressing force is applied on the carbon nanotube layer to fill theadhesive layer into the carbon nanotube layer.
 15. The method of claim13, wherein after the flexible substrate is separated from the support,the flexible substrate with the adhesive layer and the carbon nanotubelayer thereon is solidified for about 10 minutes to about 20 minutes.16. The method of claim 1, wherein in the step S4, the flexiblesubstrate and the carbon nanotube layer are cut along a linesubstantially parallel with the axis of the support.
 17. The method ofclaim 16, wherein the flexible substrate and the carbon nanotube layerare cut by a mechanical method or by an etching method.
 18. The methodof claim 1, wherein in the step S5, a plurality of wrinkles are formedin the carbon nanotube layer.
 19. The method of claim 1, wherein each ofthe plurality of wrinkles has a linear structure and is oriented along asecond direction, and the second direction is substantiallyperpendicular with the first direction.
 20. The method of claim 1,wherein in the step S6, the carbon nanotube layer comprises a first endand a second end opposite with the first end, the carbon nanotubes inthe carbon nanotube layer are substantially oriented from the first endto the second end, and the plurality of electrodes are electricallyconnected with the first end and the second end.